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How does Win8 keep CPU cooler?


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#1 moeburn

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Posted 11 July 2013 - 19:00

In Windows 7, my CPU (AMD Athlon II X4 620 @2.6ghz) idle temp was about 39*C.  In Windows 8, it idles at about 33*C!  Is it lowering my CPU clock when idle?  I noticed in Advanced Power Settings->Processor Power Management, you can no longer set the minimum and maximum cpu speed %, you can now only change System Cooling Policy from active/passive.




#2 Richard C.

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Posted 12 July 2013 - 15:07

Well in Windows 8 according to coretemp my cpu speeds seem to change wildly from as low as 7mhz to the full speed of 3.6 ghz when under load, so I'm going to say yes it lowers cpu clocks to allow cooling when it's idle.



#3 OP moeburn

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Posted 12 July 2013 - 15:30

Well in Windows 8 according to coretemp my cpu speeds seem to change wildly from as low as 7mhz to the full speed of 3.6 ghz when under load, so I'm going to say yes it lowers cpu clocks to allow cooling when it's idle.

 

Strange, I'm running Open Hardware Monitor, and it says that while my minimum CPU temp was 33.4*C (way lower than Win7), my minimum clock speeds for all 4 cores never went below 2.6ghz, and the bus speed's minimum is 200mhz, they never changed.



#4 spikey_richie

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Posted 12 July 2013 - 15:31

Try Speccy instead.



#5 REM2000

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Posted 12 July 2013 - 15:35

it's part of a power saving scheme, where possible it will try and reduce the cpu down to zero as quickly as it can. Helps keep the machine nice and cool but most importantly increases battery life. Notice a jump from around 2 - 3 hrs on my netbook to 4 - 5 hours just by switching from windows 7 to windows 8,



#6 OP moeburn

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Posted 12 July 2013 - 15:39

it's part of a power saving scheme, where possible it will try and reduce the cpu down to zero as quickly as it can. Helps keep the machine nice and cool but most importantly increases battery life. Notice a jump from around 2 - 3 hrs on my netbook to 4 - 5 hours just by switching from windows 7 to windows 8,

 

Right but according to OHM, my cpu speed never dropped.

 

So I'm running Speccy, what am I supposed to be looking at here?  I have a 2.6ghz AMD Athlon II X4 CPU.  Speccy says the bus speed is 200mhz, the stock core speed is 2.6ghz, and the stock bus speed is 200mhz, but the "rated bus speed" jumps around, usually settling at 2.0 ghz.  What's up with that?



#7 Richard C.

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Posted 12 July 2013 - 16:34

at OP, I dunno if this makes a difference but my CPU is an Intel Core i5 - 4670K



#8 Fillado

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Posted 12 July 2013 - 20:14

CPU throttling isn't anything new both on the CPU side and the OS side! Windows 7 certainly does it and has the options for it. It'll depend on what Power Plan you use too and if you've configured anything in there.

 

Saying all that I've just compared it on the same piece of hardware (3rd Gen Core i5 Laptop), with the same (Balanced) Power Plan plugged in:

 

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Everything is slightly cooler! I've tried to account for anything happening in the background such as Superfetch caching programs etc. but Windows 8 does have a slight edge.



#9 papercut2008uk

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Posted 13 July 2013 - 03:15

try running CPU-Z

 

http://www.cpuid.com...ares/cpu-z.html

 

it will show you the CPU clock speed.(along with other readings) but shows the clock speed in 'real time'



#10 OP moeburn

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Posted 13 July 2013 - 04:57

try running CPU-Z

 

http://www.cpuid.com...ares/cpu-z.html

 

it will show you the CPU clock speed.(along with other readings) but shows the clock speed in 'real time'

 

I already had CPU-Z, I tried it, and Speccy, and OHM, and they all say that my clock speed never decreased.  (Core Temp was a total dud, it didn't even report the right temperature, said my CPU was running at 29*C LOL thats my mobo temp sensor!)  HOWEVER, with all 3 running, my temperature never dropped below 39*C; one of them was breaking Windows's idle timer.  With only OHM running, the idle temp drops to 33*C, but it says the clock speed never decreased even then.

 

I'm well aware than in Windows 7 you could adjust minimum and maximum processor speed in the power options panel, but in Windows 8 those settings are gone.  I have no idea if/when my clock speed is being lowered, or if Windows 8 is just less cpu-intensive when idle, or what.  I would however like to be absolutely certain that my CPU clock isn't going to get stuck in a slow speed while I'm actually trying to use the PC.

 

Could someone who knows for a fact that their CPU clock speeds vary, test out Open Hardware Monitor (freeware, open source) and see if it reports the minimum clock speed correctly?



#11 tsupersonic

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Posted 13 July 2013 - 05:32

I highly doubt moving from Windows 7 to Windows 8 with the same CPU would make a drastic difference in temperatures, unless your power profile is different, or your hardware configuration is different, or if there is an external factor (ambient temperature) is different. Unless these temperatures were taken on the same day, I'd highly doubt it's Windows 8.


Well in Windows 8 according to coretemp my cpu speeds seem to change wildly from as low as 7mhz to the full speed of 3.6 ghz when under load, so I'm going to say yes it lowers cpu clocks to allow cooling when it's idle.

Your CPU won't downclock that far. It should go to about 800 MHz - try a different program to measure clock speeds. 



#12 OP moeburn

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Posted 13 July 2013 - 05:39

I highly doubt moving from Windows 7 to Windows 8 with the same CPU would make a drastic difference in temperatures, unless your power profile is different, or your hardware configuration is different, or if there is an external factor (ambient temperature) is different. Unless these temperatures were taken on the same day, I'd highly doubt it's Windows 8.


Your CPU won't downclock that far. It should go to about 800 MHz - try a different program to measure clock speeds. 

 

uh, I just tried 4 programs, none of them say the clock speeds went down.  

 

You might highly doubt that moving from Win7 to Win8 would change temperatures, but you'd be wrong.  Someone else here already confirmed it.  The hardware configuration is the exact same.  My idle temperatures are incredibly consistent, and do not vary by more than 5 degrees over an entire year.  My Win7 idle temp was 39-40*C, every day, for the past 3 months.  Then one day, I installed Windows 8, and my idle temp was 33-34*C, on the very same day that Win7 measured 39-40*C, using the same measuring softwares (I used SpeedFan and OHM on both OSes), which both report that they are getting the data from the same internal sensor ID (IT8720F-1).  

 

So the only explanations I can think of is that either A) my Win7 install had more CPU usage when idle (very possible, I had a ton of programs installed, but I checked CPU usage often and I would try to eliminate programs that used CPU in the background) than my Win8 install did.  Since I am running the same set of programs on Win8 that I was on Win7, I have to believe that the Windows 8 kernel itself is less CPU-intensive.  This would make sense, since they designed it to be run on battery-powered mobile devices.

 

or B) the CPU clock speed is being decreased when IDLE, but it isn't being accurately measured by any of the 4 programs I've tried.  Even though they all report the CPU clock speed in real-time, and I can see the minor variations in 100's of kHz in clock speed, so I know that they aren't just a static snapshot of a CPU clock speed in the past.



#13 CJ33

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Posted 13 July 2013 - 05:55

or you have a virus or something else ...  run this test with no other software installed.... Until then all the speculation is pointless.



#14 OP moeburn

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Posted 13 July 2013 - 05:58

or you have a virus or something else ...  run this test with no other software installed.... Until then all the speculation is pointless.

 

If there's a virus lowering my CPU temp, then that's a damn awesome virus.



#15 trieste

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Posted 13 July 2013 - 06:29

Timer coalescence?





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